Zuerch Lab
ULTRAFAST OPTICAL & X-RAY SPECTROSCOPY | ULTRAFAST PHENOMENA | ATTOSCIENCE
Zuerch Lab
ULTRAFAST OPTICAL & X-RAY SPECTROSCOPY | ULTRAFAST PHENOMENA | ATTOSCIENCE

News
Pre-Print Nonlinear Ionization Dynamics of Hot Dense Plasma Observed in a Laser-Plasma Amplifier
May 26 2020

From fusion dynamics in stars, to terrestrial lightning events, to new prospects of energy production or novel light sources, hot dense plasmas are of importance for an array of physical phenomena. Due to a plethora of correlations in highly excited matter, direct probing of isolated dynamics remains challenging. Here, the 32.8-nm emission of a high-harmonic seeded laser-plasma amplifier (LPA), using eight-fold ionized Krypton as gain medium, is ptychographically imaged in longitudinal direction in the extreme ultraviolet (XUV). In excellent agreement with ab initio spatio-temporal Maxwell-Bloch simulations, an overionization of krypton due to nonlinear laser-plasma interactions is observed. This constitutes the first experimental observation of the laser ion abundance reshaping a laser plasma amplifier. The findings have direct implications for upscaling plasma-based XUV and X-ray sources and allow modeling light-plasma interactions in extreme conditions, similar to those of the early times of the universe, with direct experimental verification.
https://arxiv.org/abs/2005.12434

Welcome Clarisse!
May 7 2020

We extend a warm welcome to our newest member Clarisse. She is an NSF REU undergraduate scholar at the University of Florida. Clarisse also enjoys synchronized swimming, painting, and hiking. We hope you enjoy the Bay!

Pre-print: Ångström-resolved Interfacial Structure in Organic-Inorganic Junctions
May 6 2020

Charge transport processes at interfaces which are governed by complex interfacial electronic structure play a crucial role in catalytic reactions, energy storage, photovoltaics, and many biological processes. Here, the first soft X-ray second harmonic generation (SXR-SHG)interfacial spectrum of a buried interface (boron/Parylene-N)is reported. SXR-SHG shows distinct spectral features that are not observed in X-ray absorption spectra, demonstrating its extraordinary interfacial sensitivity. Comparison to electronic structure calculations indicates a boron-organic separation distance of 1.9±0.1 Å, wherein changes as small as 0.1 Å result in easily detectable SXR-SHG spectral shifts (ca. 100s of meV). As SXR-SHG is inherently ultrafast and sensitive to individual atomic layers, it creates the possibility to study a variety of interfacial processes, e.g. catalysis, with ultrafast time resolution and bond specificity.
Original link to the pre-print:
https://arxiv.org/ftp/arxiv/papers/2005/2005.01905.pdf

Pre-print: Discrete dispersion scan setup for measuring few-cycle laser pulses in the mid-infrared
May 6 2020

In this work, we demonstrate a discrete dispersion scan scheme using a low number of flat windows to vary the dispersion of laser pulses in discrete steps.Monte Carlo simulations indicate that the pulse duration can be retrieved accurately with less than 10dispersion steps, which we verify experimentally by measuring few-cycle pulses and material dispersion curves at 3 and 10 μm wavelength. This minimal measuring scheme using only five optical components without the need for high-precision positioners and interferometric alignment can be readily implemented in many wavelength ranges and situations.
Original link to the pre-print:
https://arxiv.org/pdf/2004.12145.pdf

Preprint: Attosecond time-domain measurement of core-excitonic decay in magnesium oxide
May 6 2020

Excitation of ionic solids with extreme ultraviolet pulses creates localized core-excitons, which in some cases couple strongly to the lattice. Here, core-excitonic states of magnesium oxide are studied in the time domain at the Mg L2,3edge with attosecond transient reflectivity spectroscopy.Attosecond pulses trigger the excitation of these short-lived quasi particles, whose decay is perturbed by time-delayed near infrared optical pulses. Combined with a few-state theoretical model, this reveals that the optical pulse shifts the energy of bright core-exciton states as well as induces featuresarising from dark core-excitons. We report coherence lifetimes for the first two core-excitons of 2.3±0.2 and 1.6±0.5 femtoseconds and show that these short lifetimes are primarily a consequence of strong exciton-phonon coupling, disclosing the drastic influence of structural effects in this ultrafast relaxation process.
Original link to the pre-print:
https://arxiv.org/pdf/1912.12266.pdf

Retrieval of the complex-valued refractive index of germanium near the M4,5 absorption edge published!
May 6 2020

The complex-valued index of refraction of germanium in the extreme ultraviolet (XUV) is measured by multi-angle reflectance of synchrotron radiation. The resulting index of refraction is higher resolution than previously measured values. It reveals new structures attributed to transitions from the 3d-core orbitals to the Σ𝑐5,2 and the 𝑋𝑐5,2 conduction bands. Additionally, it is shown that the problem of total external reflection, which renders multi-angle reflectance measurements insensitive to the complex-valued refractive index at grazing incidence, can be overcome by employing measurements at angles of incidence away from the critical angle.
Original link to the journal:
https://www.osapublishing.org/josab/abstract.cfm?uri=josab-36-6-1716

Ptychography and Single-Shot Nanoscale Imaging with Plasma-Based Laser Sources publication
Apr 28 2020

Our recent book chapter, “Ptychography and Single-Shot Nanoscale Imaging with Plasma-Based Laser Sources” has been published in the International Conference on X-ray Lasers (Springer, 2020). We report the direct wavefront characterization of an intense ultrafast high-harmonic seeded soft X-ray laser at 32.8 nm wavelength and monitor the exit of the laser plasma amplifier depending on the arrival time of the seed pulses with respect to pump pulses.For the wavefront measurement in phase and intensity, we used high-resolution ptychography. After propagating the wavefront back to the source, we are able to observe the rear end of the plasma amplifier. We compare the characteristics of the seeded soft X-ray Laser to an unseeded one and find an increasing beam stability and lateral coherence important for lens less imaging techniques.
Original link to the Chapter:
https://link.springer.com/chapter/10.1007/978-3-030-35453-4_23

SACLA XFEL
Apr 24 2020

! Our lab member, Angelique, had the opportunity to collect SHG data(see Research) at Japan’s X-ray Free Electron Laser (XFEL) SACLA. Big thank you to all of our collaborators and experimental team!

Christmas/End of Semester Celebration!
Apr 6 2020

The crew at Jupiter’s!

New Members Joined!
Nov 1 2019

Angelique, Diego, Emma and Can joined the group. The Zürch Force has assembled!

Laser arrived!
Aug 9 2019

We are delighted to report that our ultrafast laser system arrived today in no less than 17 boxes. Many thanks to our effortless helpers on campus and the facility colleagues helping to get a temporary storage area prepared quickly. Quite some heavy lifting today, but totally worth it.

Welcome Ruoxu
Aug 8 2019

We welcome Ruoxu to our group as summer student. Ruoxu is starting her graduate research this Fall at Berkeley. She received her undergraduate degree from Grinnell College.

Zuerch Lab has moved
Aug 2 2019

We are excited to announce that the Zuerch Lab is moving from the Fritz Haber Institute in Berlin, Germany, to the University of California at Berkeley following Michael accepting an offer to join the Faculty at Berkeley in the College of Chemistry as Assistant Professor. Our new labs are under construction in the D-levels of Giauque Hall and the offices in the neighbouring Hildebrand Hall on the Berkeley Campus.

Paper on the Retrieval of the complex-valued refractive index of germanium near the M4,5 absorption edge published
Jun 1 2019

Our paper “Retrieval of the complex-valued refractive index of germanium near the M4,5 absorption edge” has been published in the Journal of the Optical Society of America B. In this work we show that the complex-valued index of refraction of germanium in the extreme ultraviolet (XUV) is measured by multi- angle reflectance of synchrotron radiation. The resulting index of refraction is higher resolution than previously measured values. It reveals new structures attributed to transitions from the 3d-core orbitals to the Σ5c,2 and the X5c,2 conduction bands. Additionally, we show that the problem of total external reflection, which renders multi-angle reflectance measurements insensitive to the complex-valued refractive index at grazing incidence, can be overcome by employing measurements at angles of incidence away from the critical angle.

Original link to the journal:
https://www.osapublishing.org/josab/abstract.cfm?uri=josab-36-6-1716

Paper on wavelength-scale ptychographic coherent diffractive imaging published
Feb 19 2019

Our paper “Wavelength-scale ptychographic coherent diffractive imaging using a high-order harmonic source”, which was the result of a collaboration between several Jena-based groups collaborating in a Forschergruppe in the State of Thuringia (2015 FGR 0094), has just been published in Scientific Reports. In this work, a full-field imaging resolution of 45 nm, corresponding to 2.5 wavelengths, was achieved using an advanced XUV source at the Institute of Applied Physics at FSU Jena. For better comparison of results in XUV imaging a Rayleigh-type criterion is used as a direct and unambiguous resolution metric for high-resolution table-top setup. This reliably qualifes this imaging system for real-world applications e.g. in biological sciences, material sciences, imaging integrated circuits and semiconductor mask inspection.

Original link to the journal:
https://www.nature.com/articles/s41598-019-38501-1

Perspective on single shot time-resolved microscopy using short wavelength table-top light sources published
Feb 13 2019

Our perspective “Towards single shot time-resolved microscopy using short wavelength table-top light sources” has been published in Structural Dynamics and was selected as featured publication. In this perspective, we present the current state of the art techniques for full-field imaging in the extreme-ultraviolet- and soft X-ray-regime which are suitable for single exposure applications as they are paramount for studying dynamics in nanoscale systems. We evaluate the performance of currently available table-top sources, with special emphasis on applications, photon flux, and coherence. Examples for applications of single shot imaging in physics, biology, and industrial applications are discussed.


Original link to the journal:
https://aca.scitation.org/doi/10.1063/1.5082686

Paper on differentiating carrier and phonon dynamics at the silicon L-edge by XUV transient absorption published
Jan 28 2019

Our paper on “Differentiating Photoexcited Carrier and Phonon Dynamics in the Δ, L, and Γ Valleys of Si(100) with Transient Extreme Ultraviolet Spectroscopy” has just been published by The Journal of Physical Chemistry. In this study, we prepared carrier populations in specific valleys in the band structure of silicon by tuning our narrow-band pump pulses in on the corresponding transition energies. We observe this specific excitation does not readily 1:1 imprint on the dynamics at the absorption edge. Using a BSE-DFT model, we find that besides the carrier population itself, contributions by excited phonon modes cause a perturbation of the core-hole transition probability that additionally modifies the observed transient XUV spectra.

Original link to the journal:
https://www.nature.com/articles/s41598-019-38501-1

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